fun foo() {
    a?.b = 1
    a?.b?.c = 1
    a?.b.c = 1

    a?.b[0] = 1
    a?.b?.c[0] = 1
    a?.b.c[0] = 1

    a?.b[0][0] = 1
    a?.b?.c[0][0] = 1
    a?.b.c[0][0] = 1

    a?.b.d() = 1
}
